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North American Commission on Stratigraphic Nomenclature (November 2005). "North American Stratigraphic Code". The American Association of Petroleum Geologists Bulletin (edisi ke-Article 13 (c)). 89 (11): 1547–1591. doi:10.1306/07050504129. Diarsipkan dari versi asli tanggal 2014-02-02. Diakses tanggal 2018-05-06.
North American Commission on Stratigraphic Nomenclature (November 2005). "North American Stratigraphic Code". The American Association of Petroleum Geologists Bulletin (edisi ke-Article 13 (c)). 89 (11): 1547–1591. doi:10.1306/07050504129. Diarsipkan dari versi asli tanggal 2014-02-02. Diakses tanggal 2018-05-06.
North American Commission on Stratigraphic Nomenclature (November 2005). "North American Stratigraphic Code". The American Association of Petroleum Geologists Bulletin (edisi ke-Article 13 (c)). 89 (11): 1547–1591. doi:10.1306/07050504129. Diarsipkan dari versi asli tanggal 2014-02-02. Diakses tanggal 2018-05-06.